Chrysotile asbestos fibers detected in the newborn pups following gavage feeding of pregnant mice

Our plain-English summary of Chrysotile asbestos fibers detected in the newborn pups following gavage feeding of pregnant mice, by A.K. Haque, I. Ali, D.M. Vrazel, et al (Journal of Toxicology and Environmental Health. Part a, 2001).

The study

• Authors: A.K. Haque, I. Ali, D.M. Vrazel, T. Uchida
• Journal: Journal of Toxicology and Environmental Health. Part a
• Published: 2001;62(1):23-31
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Female pregnant mice were fed chrysotile asbestos suspension by gavage to determine whether there is transfer of fibers to the fetuses. Groups of mice were given 2 doses of either 50 microg chrysotile suspension in 0.2 ml sterile normal saline (treated), or 0.2 ml saline (control), and were allowed to mate 2 d later. After pregnancy was confirmed, the treated and control groups received 2 additional doses of chrysotile asbestos or saline on gestational d 7 and 12. Both groups were allowed to deliver naturally, and the pups were sacrificed at 8, 1, 19, or 20 d after birth. The lungs and liver of two pups from each mother were processed for fiber counts using electron microscopy and energy-dispersive x-ray analysis (EDXA). All pups of the treated group had chrysotile fibers, while none were present in pups from controls. The mean fiber count of the lungs of treated group of pups was 780 fibers/g, and the mean fiber count of the liver was 214 fibers/g. Mean length of the fibers in the lung and liver was 18.48 microm and 18.30 microm, respectively. The fibers were thin, measuring 0.42 microm and 0.33 microm in the lung and liver, respectively. There was no significant difference in the weight gain between the treated and control group of pups. The postnatal fetal mortality of the 2 groups, 8.2% for the treated and 4.5% for the control group, were not statistically significant. To our knowledge, this is the first animal study to demonstrate that oral ingestion of chrysotile asbestos during pregnancy results in transfer of asbestos fibers to the fetuses.

In plain English

In this mouse experiment, the authors gave half of twelve young adult female ICR mice chrysotile asbestos (50 µg in 0.2 ml saline) by gavage (stomach-tube feeding), twice before mating and twice more on days 7 and 12 of pregnancy. The other half received saline only. Pups were killed 8, 11, 19 or 20 days after birth, and the lungs and liver of two pups per litter were examined by electron microscopy. No fibers were found in control pups. In pups of treated mothers, lung counts ranged from 116 to 4131 fibers/g (mean 780) and liver counts from 53 to 645 fibers/g (mean 214). Treated pups gained less weight (mean 3.85 g versus 5.16 g in controls). Deaths in the first week were higher in treated pups (5 of 61 versus 3 of 66 in controls). Neither difference was statistically significant. The authors concluded that gavage feeding of chrysotile to pregnant mice results in transfer of asbestos to the fetuses. They noted the number of animals was small, and that fibers might also have reached pups through breast milk or cage contamination, though they argued against this.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Animal experiment: pregnant mice given chrysotile by gavage (treated) or saline (control), with fiber analysis of their pups' organs
• Who was studied: Twelve young adult female ICR mice from Harlan Laboratories, half treated and half controls, and their pups (61 in the treated group, 66 in the control group). Lungs and liver of 2 pups per litter were analyzed; pups were killed on postnatal day 8, 11, 19 or 20.
• Exposure: Chrysotile asbestos, 50 µg in 0.2 ml normal saline by gavage. Two doses were given before mating and two more on gestational days 7 and 12 (four doses in total). Controls received saline on the same days.
• Main results:
  • No fibers were detected in the lungs or liver of pups from control mothers.
  • In lungs of pups from treated mothers, chrysotile counts ranged from 116 to 4131 fibers/g (mean 780, median 429).
  • In livers of pups from treated mothers, counts ranged from 53 to 645 fibers/g (mean 214, median 142).
  • Lungs of treated pups had almost three times the asbestos burden of their livers.
  • In treated pups, mean fiber length was 18.48 µm in lung (range 2.7 to 67.5 µm) and 18.30 µm in liver (range 3.59 to 43.3 µm).
  • No marked association was found between pup age and fiber counts.
  • Weight gain was greater in control pups (mean 5.16 g) than in treated pups (mean 3.85 g). The difference was not significant.
  • Deaths within 1 week after birth were 5/61 pups (8.2%) in the treated group and 3/66 pups (4.5%) in the control group. The authors reported this difference as not significant.
  • Litter size was comparable: a mean of 10 pups per litter in the treated group and 11 in the control group.
• The authors' conclusion: The authors concluded that gavage feeding of chrysotile asbestos to pregnant mice results in transfer of asbestos to the fetuses. They also concluded there was no difference in weight gain or mortality between treated and control pups.
• Limitations the authors state:
  • The number of animals was small, and the authors called for larger studies.
  • The authors acknowledged that pups might have acquired fibers through breast milk or cage contamination by maternal excreta, though they argued against this explanation.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Chrysotile.

Medical terms in this study, explained in our Lexicon: Chrysotile.

Related studies

• Transplacental transfer of asbestos in pregnant mice — A.K. Haque, D.M. Vrazel (1998)
• Teratogenicity of asbestos in mice — T. Fujitani, M. Hojo, et al. (2014)
• Placental transfer of asbestos — H.M. Cunningham, R.D. Pontefract (1974)
• A study of the effect of chrysotile fiber surface composition on genotoxicity in vitro — M.J. Keane, J.W. Stephens, et al. (1999)
• Chronic mesothelial reaction and toxicity of potassium octatitanate fibers in the pleural cavity in mice and F344 rats — M. Yokohira, Y. Nakano-Narusawa, et al. (2016)
• Comparison of Calidria chrysotile asbestos to pure tremolite: final results of the inhalation biopersistence and histopathology examination following short-term exposure — D.M. Bernstein, J. Chevalier, et al. (2005)

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